Android ListView 滚动翻页效果——加载更多

前面说过了ListView的下拉刷新效果，有些时候我们需要让ListView在滑动到最底部时，自动去向服务器请求下一页数据。这时候就需要监听的ListView的滑动状态了。

mListView.setOnScrollListener(OnScrollListener l);

OnScrollListener 内部有3个常量来记录ListView的滚动状态

int SCROLL_STATE_FLING The user had previously been scrolling using touch and had performed a fling.

int SCROLL_STATE_IDLE The view is not scrolling.

int SCROLL_STATE_TOUCH_SCROLL The user is scrolling using touch, and their finger is still on the screen

知道这些常量代表的含义，我们就可以很轻松的实现 滚动翻页的效果了。

footer_more.xml

[html] view
plaincopy

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:gravity="center_horizontal"

android:orientation="horizontal"

android:padding="15dp" >



<ProgressBar

android:id="@+id/pb_load_progress"

style="@android:style/Widget.ProgressBar.Small.Inverse"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:gravity="center"

android:indeterminate="true">

</ProgressBar>



<TextView

android:id="@+id/tv_load_more"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_marginLeft="10.0dp"

android:gravity="center"

android:text="@string/load_more_data"

android:textColor="@color/black" >

</TextView>



</LinearLayout>

activity_main.xml

[html] view
plaincopy

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

tools:context=".MainActivity" >



<TextView

android:id="@+id/tv_title"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_centerHorizontal="true"

android:layout_marginTop="5dp"

android:text="@string/load_more"

android:textSize="15sp" />



<ListView

android:id="@+id/mListView"

android:layout_below="@id/tv_title"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:cacheColorHint="@android:color/transparent" />



</RelativeLayout>

list_item.xml

[html] view
plaincopy

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="wrap_content" >



<ImageView

android:id="@+id/iv_icon"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:contentDescription="@string/app_name"

android:src="@drawable/ic_launcher" />



<TextView

android:id="@+id/tv_title"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_toRightOf="@id/iv_icon"

android:textSize="18sp"

android:textColor="@color/black"/>



<TextView

android:id="@+id/tv_content"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_toRightOf="@id/iv_icon"

android:layout_below="@id/tv_title"

android:layout_marginTop="5dp"

android:textSize="15sp"

android:textColor="@color/black"/>



</RelativeLayout>

[java] view
plaincopy

package com.example.loadmore;



import java.util.ArrayList;

import java.util.List;



import com.example.loadmore.entity.DataNews;



import android.app.Activity;

import android.content.Context;

import android.os.Bundle;

import android.os.Handler;

import android.util.Log;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AbsListView;

import android.widget.AbsListView.OnScrollListener;

import android.widget.BaseAdapter;

import android.widget.ListView;

import android.widget.ProgressBar;

import android.widget.TextView;



public class MainActivity extends Activity implements OnScrollListener {



private static final int LOAD_DATA_FINISH = 1;



private static final String TAG = MainActivity.class.getName();



private List<DataNews> dataList = new ArrayList<DataNews>();

private Handler handler = new Handler() {

public void handleMessage(android.os.Message msg) {

switch (msg.what) {

case LOAD_DATA_FINISH:

tv_load_more.setText(R.string.load_more_data);

pb_load_progress.setVisibility(View.GONE);



if(mAdapter!=null){

mAdapter.notifyDataSetChanged();

}



break;



default:

break;

}

};

};



private int startIndex = 0;

private int requestSize = 10;



private ListView mListView;



private View moreView;



private DataAdapter mAdapter;



private int lastItem;



private TextView tv_load_more;



private ProgressBar pb_load_progress;



@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);



findView();

setListener();

}



private void findView() {

LayoutInflater inflater = LayoutInflater.from(getApplicationContext());



moreView = inflater.inflate(R.layout.footer_more, null);



tv_load_more = (TextView) moreView.findViewById(R.id.tv_load_more);

pb_load_progress = (ProgressBar) moreView.findViewById(R.id.pb_load_progress);



mListView = (ListView) findViewById(R.id.mListView);



for (int i = 0; i < 10; i++) {

DataNews dn = new DataNews();

dn.setTitle("第 " + i + " 行标题");

dn.setContent("" + i + " 行内容");



dataList.add(dn);

}

mListView.addFooterView(moreView);

mAdapter = new DataAdapter(getApplicationContext());

mListView.setAdapter(mAdapter);

}



private void setListener() {

mListView.setOnScrollListener(this);

}



@Override

public void onScroll(AbsListView view, int firstVisibleItem,

int visibleItemCount, int totalItemCount) {



lastItem = firstVisibleItem + visibleItemCount - 1;



// Log.i(TAG,

// "firstVisibleItem:"+firstVisibleItem+"visibleItemCount:"+visibleItemCount+" lastItem:"+lastItem);

}



@Override

public void onScrollStateChanged(AbsListView view, int scrollState) {



if (lastItem == mAdapter.getCount()

&& scrollState == OnScrollListener.SCROLL_STATE_IDLE) {



Log.e(TAG, "load more");



startIndex += requestSize;



loadMoreData();

}

}



private void loadMoreData() {



tv_load_more.setText(R.string.loading_data);

pb_load_progress.setVisibility(View.VISIBLE);



new Thread(){



public void run() {



if (startIndex + requestSize <50) {



for (int i = startIndex; i < startIndex + requestSize; i++) {



DataNews dn = new DataNews();

dn.setTitle("增加 第 " + i + " 行标题");

dn.setContent("增加 第 " + i + " 行内容");



dataList.add(dn);

}



try {

Thread.sleep(3000);

} catch (InterruptedException e) {

e.printStackTrace();

}



handler.sendEmptyMessage(LOAD_DATA_FINISH);



}else{

handler.postDelayed(new Runnable() {



@Override

public void run() {



tv_load_more.setText(R.string.no_more_data);

pb_load_progress.setVisibility(View.GONE);



}

}, 1000);

}



};

}.start();

}



private class DataAdapter extends BaseAdapter {

private Context ctx;

private LayoutInflater inflater;



public DataAdapter(Context ctx) {

this.ctx = ctx;

inflater = LayoutInflater.from(ctx);

}



@Override

public int getCount() {



return dataList == null ? 0 : dataList.size();

}



@Override

public Object getItem(int position) {

// TODO Auto-generated method stub

return dataList.get(position);

}



@Override

public long getItemId(int position) {

// TODO Auto-generated method stub

return position;

}



@Override

public View getView(int position, View convertView, ViewGroup parent) {

ViewHolder holder;

if (convertView == null) {

convertView = inflater.inflate(R.layout.list_item, null);



holder = new ViewHolder();

holder.tv_title = (TextView) convertView

.findViewById(R.id.tv_title);

holder.tv_content = (TextView) convertView

.findViewById(R.id.tv_content);



convertView.setTag(holder);

} else {

holder = (ViewHolder) convertView.getTag();

}



DataNews dn = dataList.get(position);



holder.tv_title.setText(dn.getTitle());

holder.tv_content.setText(dn.getContent());



return convertView;

}

}



static class ViewHolder {

public TextView tv_title;

public TextView tv_content;

}



}

运行效果截图

正常状态时



滚动到底部时



没有更多数据时